It is not really a WordPress related question, more a html/css question for Stack Overflow.
But i did look at your code, you are using Bootstrap 2.3.
*/
* Bootstrap v2.3.2
*
* Copyright 2013 Twitter, Inc
* Licensed under the Apache License v2.0
* http://www.apache.org/licenses/LICENSE-2.0
*
* Designed and built with all the love in the world by @mdo and @fat.
*/
You should load the latest version (3.3.6) to use col-md-4 for your containers.